I recently purchased a 2009 MazdaSpeed 3. It now has about 1100 miles on it. Factory engine oil is 5w-30. Transaxle fluid is 75w-90. I have used Mobil 1 in my cars for years without issue, but have read some mildly disturbing things about using it in the turbo Mazda (fuel getting in the oil- oil shear). It is looking like Pennzoil Platinum is working best in these cars. Any thoughts? My transaxle is a six speed manual with a torsen LSD. I've heard all kinds of things. What about the Ford XT-M5-QS? Thanks.